Crystalline silicon solar cell and method for producing same

Abstract

The present invention aims to provide a high performance crystalline silicon solar cell. The present invention is a crystalline silicon solar cell including a first conductivity-type crystalline silicon substrate; an impurity diffusion layer formed on at least a portion of at least one surface of the crystalline silicon substrate; a buffer layer formed on at least a portion of a surface of the impurity diffusion layer; and an electrode formed on a surface of the buffer layer, wherein the electrode includes a conductive metal and a complex oxide, and the buffer layer is a layer comprising silicon, oxygen, and nitrogen.

1 . A crystalline silicon solar cell comprising:
 a first conductivity-type crystalline silicon substrate;   an impurity diffusion layer formed on at least a portion of at least one surface of the crystalline silicon substrate;   a buffer layer formed on at least a portion of a surface of the impurity diffusion layer; and   an electrode formed on a surface of the buffer layer,   wherein   the electrode comprises a conductive metal and a complex oxide, and   the buffer layer is a layer comprising silicon, oxygen, and nitrogen.   
     
     
         2 . The crystalline silicon solar cell according to  claim 1 , wherein the buffer layer comprises a conductive metallic element, silicon, oxygen, and nitrogen. 
     
     
         3 . The crystalline silicon solar cell according to  claim 2 , wherein the conductive metallic element contained in the buffer layer is silver. 
     
     
         4 . The crystalline silicon solar cell according to  claim 1 , comprising an anti-reflection film made of silicon nitride on at least a portion of the surface of the impurity diffusion layer corresponding to a portion where the electrode is not formed,
 wherein the impurity diffusion layer is a second conductivity-type impurity diffusion layer formed on a surface on a light incident side of the first conductivity-type crystalline silicon substrate, and   the electrode is an electrode formed on the surface of the light incident side of the crystalline silicon substrate.   
     
     
         5 . The crystalline silicon solar cell according to  claim 4 , wherein the electrode on the light incident side comprises a finger electrode section for electrically contacting the impurity diffusion layer, and a bus bar electrode section for electrically contacting the finger electrode section and a conductive ribbon for taking out current to the outside, wherein the buffer layer is formed between the finger electrode section and the crystalline silicon substrate, and at at least a portion directly below the finger electrode section. 
     
     
         6 . The crystalline silicon solar cell according to  claim 4 , comprising a back surface electrode formed on a back surface of the crystalline silicon substrate, opposite from the surface on the light incident side. 
     
     
         7 . The crystalline silicon solar cell according to  claim 1 , wherein the impurity diffusion layer consists of a first conductivity-type impurity diffusion layer and a second conductivity-type impurity diffusion layer both formed on a back surface of the first conductivity-type crystalline silicon substrate, opposite from the surface on the light incident side;
 the first conductivity-type impurity diffusion layer and the second conductivity-type impurity diffusion layer, each formed in a shape of a comb and disposed to interdigitate with each other;   the buffer layer includes a buffer layer formed on at least a portion of a surface of the first conductivity-type impurity diffusion layer and a buffer layer formed on at least a portion of a surface of the second conductivity-type impurity diffusion layer; and   the electrode includes a first electrode, which is formed on a surface of the buffer layer formed on the at least a portion of the surface of the first conductivity-type impurity diffusion layer, and a second electrode, which is formed on a surface of the buffer layer formed on the at least a portion of the surface of the second conductivity-type impurity diffusion layer.   
     
     
         8 . The crystalline silicon solar cell according to  claim 7 , comprising a silicon nitride film made of silicon nitride formed on at least a portion of the back surface of the first conductivity-type crystalline silicon substrate and the impurity diffusion layer corresponding to a portion where the electrodes are not formed. 
     
     
         9 . The crystalline silicon solar cell according to  claim 1 , wherein at least a portion of the buffer layer includes a silicon oxynitride film and a silicon oxide film, in the recited order, from the crystalline silicon substrate toward the electrodes. 
     
     
         10 . The crystalline silicon solar cell according to  claim 9 , wherein the buffer layer comprises conductive particulates. 
     
     
         11 . The crystalline silicon solar cell according to  claim 10 , wherein the conductive particulates have a particle size of 20 nm or less. 
     
     
         12 . The crystalline silicon solar cell according to  claim 10 , wherein the conductive particulates are present only within the silicon oxide film of the buffer layer. 
     
     
         13 . The crystalline silicon solar cell according to  claim 10 , wherein the conductive particulates are silver particulates. 
     
     
         14 . The crystalline silicon solar cell according to  claim 1 , wherein the buffer layer disposed between the electrode and the impurity diffusion layer has an area not less than 5% of an area directly below the electrode. 
     
     
         15 . The crystalline silicon solar cell according to  claim 1 , wherein the complex oxide contained in the electrode comprises molybdenum oxide, boron oxide, and bismuth oxide. 
     
     
         16 . The crystalline silicon solar cell according to  claim 15 , wherein, when the total of molybdenum oxide, boron oxide, and bismuth oxide is taken as 100 mol %, the complex oxide contains 25-65 mol % of molybdenum oxide, 5-45 mol % of boron oxide, and 25-35 mol % of bismuth oxide. 
     
     
         17 . A method for producing a crystalline silicon solar cell, the method comprising:
 preparing a first conductivity-type crystalline silicon substrate;   forming an impurity diffusion layer on at least a portion of at least one surface of the crystalline silicon substrate;   forming a silicon nitride film on a surface of the impurity diffusion layer; and   printing and firing a conductive paste on a surface of the silicon nitride film, which is formed on the surface of the impurity diffusion layer, to form an electrode and a buffer layer between the electrode and the impurity diffusion layer,   wherein the buffer layer is a layer comprising silicon, oxygen, and nitrogen.   
     
     
         18 . The method for producing a crystalline silicon solar cell according to  claim 17 , wherein the buffer layer is a layer comprising a conductive metallic element, silicon, oxygen, and nitrogen. 
     
     
         19 . The method for producing a crystalline silicon solar cell according to  claim 18 , wherein the conductive metallic element contained in the buffer layer is silver. 
     
     
         20 . The method for producing a crystalline silicon solar cell according to  claim 17 ,
 wherein the impurity diffusion layer is a second conductivity-type impurity diffusion layer formed on a surface on the light incident side of the first conductivity-type crystalline silicon substrate, and   the electrode is an electrode formed on the surface on the light incident side of the crystalline silicon substrate.   
     
     
         21 - 34 . (canceled)